nodemcu-firmware/app/modules/u8g.c

// Module for U8glib

#include "module.h"
#include "lauxlib.h"
#include "lmem.h"
#include "platform.h"

#include "u8g.h"
#include "u8g_glue.h"

#include "u8g_config.h"


// helper function: retrieve and check userdata argument
static lu8g_userdata_t *get_lud( lua_State *L )
{
    lu8g_userdata_t *lud = (lu8g_userdata_t *)luaL_checkudata(L, 1, "u8g.display");
    luaL_argcheck(L, lud, 1, "u8g.display expected");
    return lud;
}

// helper function: retrieve given number of integer arguments
static void lu8g_get_int_args( lua_State *L, uint8_t stack, uint8_t num, u8g_uint_t *args)
{
    while (num-- > 0)
    {
        *args++ = luaL_checkinteger( L, stack++ );
    }
}


// Lua: u8g.begin( self )
static int lu8g_begin( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_Begin( LU8G );

    return 0;
}

// Lua: u8g.setFont( self, font )
static int lu8g_setFont( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_fntpgm_uint8_t *font = (u8g_fntpgm_uint8_t *)lua_touserdata( L, 2 );
    if (font != NULL)
        u8g_SetFont( LU8G, font );
    else
        luaL_argerror(L, 2, "font data expected");

    return 0;
}

// Lua: u8g.setFontRefHeightAll( self )
static int lu8g_setFontRefHeightAll( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontRefHeightAll( LU8G );

    return 0;
}

// Lua: u8g.setFontRefHeightExtendedText( self )
static int lu8g_setFontRefHeightExtendedText( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontRefHeightExtendedText( LU8G );

    return 0;
}

// Lua: u8g.setFontRefHeightText( self )
static int lu8g_setFontRefHeightText( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontRefHeightText( LU8G );

    return 0;
}

// Lua: u8g.setDefaultBackgroundColor( self )
static int lu8g_setDefaultBackgroundColor( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetDefaultBackgroundColor( LU8G );

    return 0;
}

// Lua: u8g.setDefaultForegroundColor( self )
static int lu8g_setDefaultForegroundColor( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetDefaultForegroundColor( LU8G );

    return 0;
}

// Lua: u8g.setFontPosBaseline( self )
static int lu8g_setFontPosBaseline( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontPosBaseline( LU8G );

    return 0;
}

// Lua: u8g.setFontPosBottom( self )
static int lu8g_setFontPosBottom( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontPosBottom( LU8G );

    return 0;
}

// Lua: u8g.setFontPosCenter( self )
static int lu8g_setFontPosCenter( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontPosCenter( LU8G );

    return 0;
}

// Lua: u8g.setFontPosTop( self )
static int lu8g_setFontPosTop( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetFontPosTop( LU8G );

    return 0;
}

// Lua: int = u8g.getFontAscent( self )
static int lu8g_getFontAscent( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetFontAscent( LU8G ) );

    return 1;
}

// Lua: int = u8g.getFontDescent( self )
static int lu8g_getFontDescent( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetFontDescent( LU8G ) );

    return 1;
}

// Lua: int = u8g.getFontLineSpacing( self )
static int lu8g_getFontLineSpacing( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetFontLineSpacing( LU8G ) );

    return 1;
}

// Lua: int = u8g.getMode( self )
static int lu8g_getMode( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetMode( LU8G ) );

    return 1;
}

// Lua: u8g.setContrast( self, constrast )
static int lu8g_setContrast( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetContrast( LU8G, luaL_checkinteger( L, 2 ) );

    return 0;
}

// Lua: u8g.setColorIndex( self, color )
static int lu8g_setColorIndex( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetColorIndex( LU8G, luaL_checkinteger( L, 2 ) );

    return 0;
}

// Lua: int = u8g.getColorIndex( self )
static int lu8g_getColorIndex( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetColorIndex( LU8G ) );

    return 1;
}

static int lu8g_generic_drawStr( lua_State *L, uint8_t rot )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[2];
    lu8g_get_int_args( L, 2, 2, args );

    const char *s = luaL_checkstring( L, (1+2) + 1 );
    if (s == NULL)
        return 0;

    switch (rot)
    {
    case 1:
        lua_pushinteger( L, u8g_DrawStr90( LU8G, args[0], args[1], s ) );
        break;
    case 2:
        lua_pushinteger( L, u8g_DrawStr180( LU8G, args[0], args[1], s ) );
        break;
    case 3:
        lua_pushinteger( L, u8g_DrawStr270( LU8G, args[0], args[1], s ) );
        break;
    default:
        lua_pushinteger( L, u8g_DrawStr( LU8G, args[0], args[1], s ) );
        break;
    }

    return 1;
}


// Lua: pix_len = u8g.drawStr( self, x, y, string )
static int lu8g_drawStr( lua_State *L )
{
    return lu8g_generic_drawStr( L, 0 );
}

// Lua: pix_len = u8g.drawStr90( self, x, y, string )
static int lu8g_drawStr90( lua_State *L )
{
    return lu8g_generic_drawStr( L, 1 );
}

// Lua: pix_len = u8g.drawStr180( self, x, y, string )
static int lu8g_drawStr180( lua_State *L )
{
    return lu8g_generic_drawStr( L, 2 );
}

// Lua: pix_len = u8g.drawStr270( self, x, y, string )
static int lu8g_drawStr270( lua_State *L )
{
    return lu8g_generic_drawStr( L, 3 );
}

// Lua: u8g.drawLine( self, x1, y1, x2, y2 )
static int lu8g_drawLine( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    u8g_DrawLine( LU8G, args[0], args[1], args[2], args[3] );

    return 0;
}

// Lua: u8g.drawTriangle( self, x0, y0, x1, y1, x2, y2 )
static int lu8g_drawTriangle( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[6];
    lu8g_get_int_args( L, 2, 6, args );

    u8g_DrawTriangle( LU8G, args[0], args[1], args[2], args[3], args[4], args[5] );

    return 0;
}

// Lua: u8g.drawBox( self, x, y, width, height )
static int lu8g_drawBox( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    u8g_DrawBox( LU8G, args[0], args[1], args[2], args[3] );

    return 0;
}

// Lua: u8g.drawRBox( self, x, y, width, height, radius )
static int lu8g_drawRBox( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[5];
    lu8g_get_int_args( L, 2, 5, args );

    u8g_DrawRBox( LU8G, args[0], args[1], args[2], args[3], args[4] );

    return 0;
}

// Lua: u8g.drawFrame( self, x, y, width, height )
static int lu8g_drawFrame( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    u8g_DrawFrame( LU8G, args[0], args[1], args[2], args[3] );

    return 0;
}

// Lua: u8g.drawRFrame( self, x, y, width, height, radius )
static int lu8g_drawRFrame( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[5];
    lu8g_get_int_args( L, 2, 5, args );

    u8g_DrawRFrame( LU8G, args[0], args[1], args[2], args[3], args[4] );

    return 0;
}

// Lua: u8g.drawDisc( self, x0, y0, rad, opt = U8G_DRAW_ALL )
static int lu8g_drawDisc( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[3];
    lu8g_get_int_args( L, 2, 3, args );

    u8g_uint_t opt = luaL_optinteger( L, (1+3) + 1, U8G_DRAW_ALL );

    u8g_DrawDisc( LU8G, args[0], args[1], args[2], opt );

    return 0;
}

// Lua: u8g.drawCircle( self, x0, y0, rad, opt = U8G_DRAW_ALL )
static int lu8g_drawCircle( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[3];
    lu8g_get_int_args( L, 2, 3, args );

    u8g_uint_t opt = luaL_optinteger( L, (1+3) + 1, U8G_DRAW_ALL );

    u8g_DrawCircle( LU8G, args[0], args[1], args[2], opt );

    return 0;
}

// Lua: u8g.drawEllipse( self, x0, y0, rx, ry, opt = U8G_DRAW_ALL )
static int lu8g_drawEllipse( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    u8g_uint_t opt = luaL_optinteger( L, (1+4) + 1, U8G_DRAW_ALL );

    u8g_DrawEllipse( LU8G, args[0], args[1], args[2], args[3], opt );

    return 0;
}

// Lua: u8g.drawFilledEllipse( self, x0, y0, rx, ry, opt = U8G_DRAW_ALL )
static int lu8g_drawFilledEllipse( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    u8g_uint_t opt = luaL_optinteger( L, (1+4) + 1, U8G_DRAW_ALL );

    u8g_DrawFilledEllipse( LU8G, args[0], args[1], args[2], args[3], opt );

    return 0;
}

// Lua: u8g.drawPixel( self, x, y )
static int lu8g_drawPixel( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[2];
    lu8g_get_int_args( L, 2, 2, args );

    u8g_DrawPixel( LU8G, args[0], args[1] );

    return 0;
}

// Lua: u8g.drawHLine( self, x, y, width )
static int lu8g_drawHLine( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[3];
    lu8g_get_int_args( L, 2, 3, args );

    u8g_DrawHLine( LU8G, args[0], args[1], args[2] );

    return 0;
}

// Lua: u8g.drawVLine( self, x, y, width )
static int lu8g_drawVLine( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[3];
    lu8g_get_int_args( L, 2, 3, args );

    u8g_DrawVLine( LU8G, args[0], args[1], args[2] );

    return 0;
}

// Lua: u8g.drawXBM( self, x, y, width, height, data )
static int lu8g_drawXBM( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    const char *xbm_data = luaL_checkstring( L, (1+4) + 1 );
    if (xbm_data == NULL)
        return 0;

    u8g_DrawXBM( LU8G, args[0], args[1], args[2], args[3], (const uint8_t *)xbm_data );

    return 0;
}

// Lua: u8g.drawBitmap( self, x, y, count, height, data )
static int lu8g_drawBitmap( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t args[4];
    lu8g_get_int_args( L, 2, 4, args );

    const char *bm_data = luaL_checkstring( L, (1+4) + 1 );
    if (bm_data == NULL)
        return 0;

    u8g_DrawBitmap( LU8G, args[0], args[1], args[2], args[3], (const uint8_t *)bm_data );

    return 0;
}

// Lua: u8g.setScale2x2( self )
static int lu8g_setScale2x2( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetScale2x2( LU8G );

    return 0;
}

// Lua: u8g.undoScale( self )
static int lu8g_undoScale( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_UndoScale( LU8G );

    return 0;
}

// Lua: u8g.firstPage( self )
static int lu8g_firstPage( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_FirstPage( LU8G );

    return 0;
}

// Lua: bool = u8g.nextPage( self )
static int lu8g_nextPage( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushboolean( L, u8g_NextPage( LU8G ) );

    return 1;
}

// Lua: u8g.sleepOn( self )
static int lu8g_sleepOn( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SleepOn( LU8G );

    return 0;
}

// Lua: u8g.sleepOff( self )
static int lu8g_sleepOff( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SleepOff( LU8G );

    return 0;
}

// Lua: u8g.setRot90( self )
static int lu8g_setRot90( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetRot90( LU8G );

    return 0;
}

// Lua: u8g.setRot180( self )
static int lu8g_setRot180( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetRot180( LU8G );

    return 0;
}

// Lua: u8g.setRot270( self )
static int lu8g_setRot270( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_SetRot270( LU8G );

    return 0;
}

// Lua: u8g.undoRotation( self )
static int lu8g_undoRotation( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_UndoRotation( LU8G );

    return 0;
}

// Lua: width = u8g.getWidth( self )
static int lu8g_getWidth( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetWidth( LU8G ) );

    return 1;
}

// Lua: height = u8g.getHeight( self )
static int lu8g_getHeight( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetHeight( LU8G ) );

    return 1;
}

// Lua: width = u8g.getStrWidth( self, string )
static int lu8g_getStrWidth( lua_State *L )
{
   lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    const char *s = luaL_checkstring( L, 2 );
    if (s == NULL)
        return 0;

    lua_pushinteger( L, u8g_GetStrWidth( LU8G, s ) );

    return 1;
}

// Lua: u8g.setFontLineSpacingFactor( self, factor )
static int lu8g_setFontLineSpacingFactor( lua_State *L )
{
   lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    u8g_uint_t factor = luaL_checkinteger( L, 2 );

    u8g_SetFontLineSpacingFactor( LU8G, factor );

    return 0;
}


// ------------------------------------------------------------
// comm functions
//
#define I2C_CMD_MODE    0x000
#define I2C_DATA_MODE   0x040

#define ESP_I2C_ID 0


static uint8_t do_i2c_start(uint8_t id, uint8_t sla)
{
    platform_i2c_send_start( id );

    // ignore return value -> tolerate missing ACK
    platform_i2c_send_address( id, sla, PLATFORM_I2C_DIRECTION_TRANSMITTER );

    return 1;
}

static uint8_t u8g_com_esp8266_ssd_start_sequence(u8g_t *u8g)
{
    /* are we requested to set the a0 state? */
    if ( u8g->pin_list[U8G_PI_SET_A0] == 0 )
        return 1;

    /* setup bus, might be a repeated start */
    if ( do_i2c_start( ESP_I2C_ID, u8g->i2c_addr ) == 0 )
        return 0;
    if ( u8g->pin_list[U8G_PI_A0_STATE] == 0 )
    {
        // ignore return value -> tolerate missing ACK
        if ( platform_i2c_send_byte( ESP_I2C_ID, I2C_CMD_MODE ) == 0 )
            ; //return 0;
    }
    else
    {
        platform_i2c_send_byte( ESP_I2C_ID, I2C_DATA_MODE );
    }

    u8g->pin_list[U8G_PI_SET_A0] = 0;
    return 1;
}


static void lu8g_digital_write( u8g_t *u8g, uint8_t pin_index, uint8_t value )
{
    uint8_t pin;

    pin = u8g->pin_list[pin_index];
    if ( pin != U8G_PIN_NONE )
        platform_gpio_write( pin, value );
}

void u8g_Delay(u8g_t *u8g, uint16_t msec)
{
    const uint16_t chunk = 50;

    if (u8g->use_delay == 0)
        return;

    while (msec > chunk)
    {
        os_delay_us( chunk*1000 );
        msec -= chunk;
    }
    if (msec > 0)
        os_delay_us( msec*1000 );
}
void u8g_MicroDelay(void)
{
    os_delay_us( 1 );
}
void u8g_10MicroDelay(void)
{
    os_delay_us( 10 );
}


uint8_t u8g_com_esp8266_hw_spi_fn(u8g_t *u8g, uint8_t msg, uint8_t arg_val, void *arg_ptr)
{
    switch(msg)
    {
    case U8G_COM_MSG_STOP:
        break;
    
    case U8G_COM_MSG_INIT:
        // we assume that the SPI interface was already initialized
        // just care for the /CS and D/C pins
        lu8g_digital_write( u8g, U8G_PI_CS, PLATFORM_GPIO_HIGH );
        platform_gpio_mode( u8g->pin_list[U8G_PI_CS], PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT );
        platform_gpio_mode( u8g->pin_list[U8G_PI_A0], PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT );
        break;
    
    case U8G_COM_MSG_ADDRESS:                     /* define cmd (arg_val = 0) or data mode (arg_val = 1) */
        lu8g_digital_write( u8g, U8G_PI_A0, arg_val == 0 ? PLATFORM_GPIO_LOW : PLATFORM_GPIO_HIGH );
        break;

    case U8G_COM_MSG_CHIP_SELECT:
        if (arg_val == 0)
        {
            /* disable */
            lu8g_digital_write( u8g, U8G_PI_CS, PLATFORM_GPIO_HIGH );
        }
        else
        {
            /* enable */
            //u8g_com_arduino_digital_write(u8g, U8G_PI_SCK, LOW);
            lu8g_digital_write( u8g, U8G_PI_CS, PLATFORM_GPIO_LOW );
        }
        break;
      
    case U8G_COM_MSG_RESET:
        if ( u8g->pin_list[U8G_PI_RESET] != U8G_PIN_NONE )
            lu8g_digital_write( u8g, U8G_PI_RESET, arg_val == 0 ? PLATFORM_GPIO_LOW : PLATFORM_GPIO_HIGH );
        break;
    
    case U8G_COM_MSG_WRITE_BYTE:
        platform_spi_send( 1, 8, arg_val );
        break;
    
    case U8G_COM_MSG_WRITE_SEQ:
    case U8G_COM_MSG_WRITE_SEQ_P:
        {
            register uint8_t *ptr = arg_ptr;
            while( arg_val > 0 )
            {
                platform_spi_send( 1, 8, *ptr++ );
                arg_val--;
            }
        }
        break;
    }
    return 1;
}


uint8_t u8g_com_esp8266_ssd_i2c_fn(u8g_t *u8g, uint8_t msg, uint8_t arg_val, void *arg_ptr)
{
    switch(msg)
    {
    case U8G_COM_MSG_INIT:
        // we assume that the i2c bus was already initialized
        //u8g_i2c_init(u8g->pin_list[U8G_PI_I2C_OPTION]);

        break;
    
    case U8G_COM_MSG_STOP:
        break;

    case U8G_COM_MSG_RESET:
        /* Currently disabled, but it could be enable. Previous restrictions have been removed */
        /* u8g_com_arduino_digital_write(u8g, U8G_PI_RESET, arg_val); */
        break;
      
    case U8G_COM_MSG_CHIP_SELECT:
        u8g->pin_list[U8G_PI_A0_STATE] = 0;
        u8g->pin_list[U8G_PI_SET_A0] = 1;		/* force a0 to set again, also forces start condition */
        if ( arg_val == 0 )
        {
            /* disable chip, send stop condition */
            platform_i2c_send_stop( ESP_I2C_ID );
        }
        else
        {
            /* enable, do nothing: any byte writing will trigger the i2c start */
        }
        break;

    case U8G_COM_MSG_WRITE_BYTE:
        //u8g->pin_list[U8G_PI_SET_A0] = 1;
        if ( u8g_com_esp8266_ssd_start_sequence(u8g) == 0 )
            return platform_i2c_send_stop( ESP_I2C_ID ), 0;
        // ignore return value -> tolerate missing ACK
        if ( platform_i2c_send_byte( ESP_I2C_ID, arg_val) == 0 )
            ; //return platform_i2c_send_stop( ESP_I2C_ID ), 0;
        // platform_i2c_send_stop( ESP_I2C_ID );
        break;
    
    case U8G_COM_MSG_WRITE_SEQ:
    case U8G_COM_MSG_WRITE_SEQ_P:
        //u8g->pin_list[U8G_PI_SET_A0] = 1;
        if ( u8g_com_esp8266_ssd_start_sequence(u8g) == 0 )
            return platform_i2c_send_stop( ESP_I2C_ID ), 0;
        {
            register uint8_t *ptr = arg_ptr;
            while( arg_val > 0 )
            {
                // ignore return value -> tolerate missing ACK
                if ( platform_i2c_send_byte( ESP_I2C_ID, *ptr++) == 0 )
                    ; //return platform_i2c_send_stop( ESP_I2C_ID ), 0;
                arg_val--;
            }
        }
        // platform_i2c_send_stop( ESP_I2C_ID );
        break;

    case U8G_COM_MSG_ADDRESS:                     /* define cmd (arg_val = 0) or data mode (arg_val = 1) */
        u8g->pin_list[U8G_PI_A0_STATE] = arg_val;
        u8g->pin_list[U8G_PI_SET_A0] = 1;		/* force a0 to set again */
    
        break;
    }
    return 1;
}


// device destructor
static int lu8g_close_display( lua_State *L )
{
    lu8g_userdata_t *lud;

    if ((lud = get_lud( L )) == NULL)
        return 0;

    if (lud->cb_ref != LUA_NOREF) {
        // this is the fb_rle device
        u8g_dev_t *fb_dev = LU8G->dev;
        u8g_pb_t *fb_dev_pb = (u8g_pb_t *)(fb_dev->dev_mem);
        uint8_t *fb_dev_buf = fb_dev_pb->buf;

        luaM_free( L, fb_dev_buf );
        luaM_free( L, fb_dev_pb );
        luaM_free( L, fb_dev );

        luaL_unref( L, lud->cb_ref, LUA_REGISTRYINDEX );
    }

    return 0;
}


// ***************************************************************************
// Device constructors
//
//
// I2C based devices will use this function template to implement the Lua binding.
#undef U8G_DISPLAY_TABLE_ENTRY
#define U8G_DISPLAY_TABLE_ENTRY(device)                                 \
    static int lu8g_ ## device( lua_State *L )                          \
    {                                                                   \
        unsigned addr = luaL_checkinteger( L, 1 );                      \
        unsigned del  = luaL_optinteger( L, 2, 0 );                     \
                                                                        \
        if (addr == 0)                                                  \
            return luaL_error( L, "i2c address required" );             \
                                                                        \
        lu8g_userdata_t *lud = (lu8g_userdata_t *) lua_newuserdata( L, sizeof( lu8g_userdata_t ) ); \
        lud->cb_ref = LUA_NOREF;                                        \
                                                                        \
        lud->u8g.i2c_addr = (uint8_t)addr;                              \
        lud->u8g.use_delay = del > 0 ? 1 : 0;                           \
                                                                        \
        u8g_InitI2C( LU8G, &u8g_dev_ ## device, U8G_I2C_OPT_NONE);      \
                                                                        \
        /* set its metatable */                                         \
        luaL_getmetatable(L, "u8g.display");                            \
        lua_setmetatable(L, -2);                                        \
                                                                        \
        return 1;                                                       \
    } 
//
// Unroll the display table and insert binding functions for I2C based displays.
U8G_DISPLAY_TABLE_I2C
//
//
//
// SPI based devices will use this function template to implement the Lua binding.
#undef U8G_DISPLAY_TABLE_ENTRY
#define U8G_DISPLAY_TABLE_ENTRY(device)                                 \
    static int lu8g_ ## device( lua_State *L )                          \
    {                                                                   \
        unsigned cs = luaL_checkinteger( L, 1 );                        \
        if (cs == 0)                                                    \
            return luaL_error( L, "CS pin required" );                  \
        unsigned dc = luaL_checkinteger( L, 2 );                        \
        if (dc == 0)                                                    \
            return luaL_error( L, "D/C pin required" );                 \
        unsigned res = luaL_optinteger( L, 3, U8G_PIN_NONE );           \
        unsigned del = luaL_optinteger( L, 4, 0 );                      \
                                                                        \
        lu8g_userdata_t *lud = (lu8g_userdata_t *) lua_newuserdata( L, sizeof( lu8g_userdata_t ) ); \
        lud->cb_ref = LUA_NOREF;                                        \
                                                                        \
        lud->u8g.use_delay = del > 0 ? 1 : 0;                           \
                                                                        \
        u8g_InitHWSPI( LU8G, &u8g_dev_ ## device, cs, dc, res );        \
                                                                        \
        /* set its metatable */                                         \
        luaL_getmetatable(L, "u8g.display");                            \
        lua_setmetatable(L, -2);                                        \
                                                                        \
        return 1;                                                       \
    }
//
// Unroll the display table and insert binding functions for SPI based displays.
U8G_DISPLAY_TABLE_SPI
//
//
//
// This display forwards the framebuffer contents as run-length encoded chunks to a Lua callback
static int lu8g_fb_rle( lua_State *L ) {
    lu8g_userdata_t *lud;

    if ((lua_type( L, 1 ) != LUA_TFUNCTION) &&
        (lua_type( L, 1 ) != LUA_TLIGHTFUNCTION)) {
        luaL_typerror( L, 1, "function" );
    }

    int width = luaL_checkint( L, 2 );
    int height = luaL_checkint( L, 3 );

    luaL_argcheck( L, (width > 0) && (width < 256) && ((width % 8) == 0), 2, "invalid width" );
    luaL_argcheck( L, (height > 0) && (height < 256) && ((height % 8) == 0), 3, "invalid height" );

    // construct display device structures manually because width and height are configurable
    uint8_t *fb_dev_buf = (uint8_t *)luaM_malloc( L, width );

    u8g_pb_t *fb_dev_pb = (u8g_pb_t *)luaM_malloc( L, sizeof( u8g_pb_t ) );
    fb_dev_pb->p.page_height  = 8;
    fb_dev_pb->p.total_height = height;
    fb_dev_pb->p.page_y0      = 0;
    fb_dev_pb->p.page_y1      = 0;
    fb_dev_pb->p.page         = 0;
    fb_dev_pb->width = width;
    fb_dev_pb->buf   = fb_dev_buf;

    u8g_dev_t *fb_dev = (u8g_dev_t *)luaM_malloc( L, sizeof( u8g_dev_t ) );
    fb_dev->dev_fn = u8g_dev_gen_fb_fn;
    fb_dev->dev_mem = fb_dev_pb;
    fb_dev->com_fn = u8g_com_esp8266_fbrle_fn;

    lud = (lu8g_userdata_t *) lua_newuserdata( L, sizeof( lu8g_userdata_t ) );
    lua_pushvalue( L, 1 );  // copy argument (func) to the top of stack
    lud->cb_ref = luaL_ref( L, LUA_REGISTRYINDEX );

    /* set metatable for userdata */
    luaL_getmetatable(L, "u8g.display");
    lua_setmetatable(L, -2);

    u8g_Init8BitFixedPort( LU8G, fb_dev, width, height, 0, 0, 0);

    return 1;
}
//
// ***************************************************************************


// Module function map
static const LUA_REG_TYPE lu8g_display_map[] = {
  { LSTRKEY( "begin" ),                        LFUNCVAL( lu8g_begin ) },
  { LSTRKEY( "drawBitmap" ),                   LFUNCVAL( lu8g_drawBitmap ) },
  { LSTRKEY( "drawBox" ),                      LFUNCVAL( lu8g_drawBox ) },
  { LSTRKEY( "drawCircle" ),                   LFUNCVAL( lu8g_drawCircle ) },
  { LSTRKEY( "drawDisc" ),                     LFUNCVAL( lu8g_drawDisc ) },
  { LSTRKEY( "drawEllipse" ),                  LFUNCVAL( lu8g_drawEllipse ) },
  { LSTRKEY( "drawFilledEllipse" ),            LFUNCVAL( lu8g_drawFilledEllipse ) },
  { LSTRKEY( "drawFrame" ),                    LFUNCVAL( lu8g_drawFrame ) },
  { LSTRKEY( "drawHLine" ),                    LFUNCVAL( lu8g_drawHLine ) },
  { LSTRKEY( "drawLine" ),                     LFUNCVAL( lu8g_drawLine ) },
  { LSTRKEY( "drawPixel" ),                    LFUNCVAL( lu8g_drawPixel ) },
  { LSTRKEY( "drawRBox" ),                     LFUNCVAL( lu8g_drawRBox ) },
  { LSTRKEY( "drawRFrame" ),                   LFUNCVAL( lu8g_drawRFrame ) },
  { LSTRKEY( "drawStr" ),                      LFUNCVAL( lu8g_drawStr ) },
  { LSTRKEY( "drawStr90" ),                    LFUNCVAL( lu8g_drawStr90 ) },
  { LSTRKEY( "drawStr180" ),                   LFUNCVAL( lu8g_drawStr180 ) },
  { LSTRKEY( "drawStr270" ),                   LFUNCVAL( lu8g_drawStr270 ) },
  { LSTRKEY( "drawTriangle" ),                 LFUNCVAL( lu8g_drawTriangle ) },
  { LSTRKEY( "drawVLine" ),                    LFUNCVAL( lu8g_drawVLine ) },
  { LSTRKEY( "drawXBM" ),                      LFUNCVAL( lu8g_drawXBM ) },
  { LSTRKEY( "firstPage" ),                    LFUNCVAL( lu8g_firstPage ) },
  { LSTRKEY( "getColorIndex" ),                LFUNCVAL( lu8g_getColorIndex ) },
  { LSTRKEY( "getFontAscent" ),                LFUNCVAL( lu8g_getFontAscent ) },
  { LSTRKEY( "getFontDescent" ),               LFUNCVAL( lu8g_getFontDescent ) },
  { LSTRKEY( "getFontLineSpacing" ),           LFUNCVAL( lu8g_getFontLineSpacing ) },
  { LSTRKEY( "getHeight" ),                    LFUNCVAL( lu8g_getHeight ) },
  { LSTRKEY( "getMode" ),                      LFUNCVAL( lu8g_getMode ) },
  { LSTRKEY( "getStrWidth" ),                  LFUNCVAL( lu8g_getStrWidth ) },
  { LSTRKEY( "getWidth" ),                     LFUNCVAL( lu8g_getWidth ) },
  { LSTRKEY( "nextPage" ),                     LFUNCVAL( lu8g_nextPage ) },
  { LSTRKEY( "setContrast" ),                  LFUNCVAL( lu8g_setContrast ) },
  { LSTRKEY( "setColorIndex" ),                LFUNCVAL( lu8g_setColorIndex ) },
  { LSTRKEY( "setDefaultBackgroundColor" ),    LFUNCVAL( lu8g_setDefaultBackgroundColor ) },
  { LSTRKEY( "setDefaultForegroundColor" ),    LFUNCVAL( lu8g_setDefaultForegroundColor ) },
  { LSTRKEY( "setFont" ),                      LFUNCVAL( lu8g_setFont ) },
  { LSTRKEY( "setFontLineSpacingFactor" ),     LFUNCVAL( lu8g_setFontLineSpacingFactor ) },
  { LSTRKEY( "setFontPosBaseline" ),           LFUNCVAL( lu8g_setFontPosBaseline ) },
  { LSTRKEY( "setFontPosBottom" ),             LFUNCVAL( lu8g_setFontPosBottom ) },
  { LSTRKEY( "setFontPosCenter" ),             LFUNCVAL( lu8g_setFontPosCenter ) },
  { LSTRKEY( "setFontPosTop" ),                LFUNCVAL( lu8g_setFontPosTop ) },
  { LSTRKEY( "setFontRefHeightAll" ),          LFUNCVAL( lu8g_setFontRefHeightAll ) },
  { LSTRKEY( "setFontRefHeightExtendedText" ), LFUNCVAL( lu8g_setFontRefHeightExtendedText ) },
  { LSTRKEY( "setFontRefHeightText" ),         LFUNCVAL( lu8g_setFontRefHeightText ) },
  { LSTRKEY( "setRot90" ),                     LFUNCVAL( lu8g_setRot90 ) },
  { LSTRKEY( "setRot180" ),                    LFUNCVAL( lu8g_setRot180 ) },
  { LSTRKEY( "setRot270" ),                    LFUNCVAL( lu8g_setRot270 ) },
  { LSTRKEY( "setScale2x2" ),                  LFUNCVAL( lu8g_setScale2x2 ) },
  { LSTRKEY( "sleepOff" ),                     LFUNCVAL( lu8g_sleepOff ) },
  { LSTRKEY( "sleepOn" ),                      LFUNCVAL( lu8g_sleepOn ) },
  { LSTRKEY( "undoRotation" ),                 LFUNCVAL( lu8g_undoRotation ) },
  { LSTRKEY( "undoScale" ),                    LFUNCVAL( lu8g_undoScale ) },
  { LSTRKEY( "__gc" ),                         LFUNCVAL( lu8g_close_display ) },
  { LSTRKEY( "__index" ),                      LROVAL( lu8g_display_map ) },
  { LNILKEY, LNILVAL }
};

#undef U8G_DISPLAY_TABLE_ENTRY
#undef U8G_FONT_TABLE_ENTRY

static const LUA_REG_TYPE lu8g_map[] = {
#define U8G_DISPLAY_TABLE_ENTRY(device) \
  { LSTRKEY( #device ),            LFUNCVAL ( lu8g_ ##device ) },
  U8G_DISPLAY_TABLE_I2C
  U8G_DISPLAY_TABLE_SPI
// Register fonts
#define U8G_FONT_TABLE_ENTRY(font) \
  { LSTRKEY( #font ),              LUDATA( (void *)(u8g_ ## font) ) },
  U8G_FONT_TABLE
  //
  { LSTRKEY( "fb_rle" ),  LFUNCVAL( lu8g_fb_rle ) },
  // Options for circle/ ellipse drawing
  { LSTRKEY( "DRAW_UPPER_RIGHT" ), LNUMVAL( U8G_DRAW_UPPER_RIGHT ) },
  { LSTRKEY( "DRAW_UPPER_LEFT" ),  LNUMVAL( U8G_DRAW_UPPER_LEFT ) },
  { LSTRKEY( "DRAW_LOWER_RIGHT" ), LNUMVAL( U8G_DRAW_LOWER_RIGHT ) },
  { LSTRKEY( "DRAW_LOWER_LEFT" ),  LNUMVAL( U8G_DRAW_LOWER_LEFT ) },
  { LSTRKEY( "DRAW_ALL" ),         LNUMVAL( U8G_DRAW_ALL ) },
  // Display modes
  { LSTRKEY( "MODE_BW" ),          LNUMVAL( U8G_MODE_BW ) },
  { LSTRKEY( "MODE_GRAY2BIT" ),    LNUMVAL( U8G_MODE_GRAY2BIT ) },
  { LSTRKEY( "__metatable" ), LROVAL( lu8g_map ) },
  { LNILKEY, LNILVAL }
};

int luaopen_u8g( lua_State *L ) {
  luaL_rometatable(L, "u8g.display", (void *)lu8g_display_map);  // create metatable
  return 0;
}

NODEMCU_MODULE(U8G, "u8g", lu8g_map, luaopen_u8g);